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How Design for Misuse Creates Safer Products

(This post is based on the video, “Design for Misuse,” in the Design Defined: Design Principles Explained series.)

When you’re designing a device, it’s tempting to assume that your users will interact with the product as intended. But it’s impossible to perfectly predict human behavior, and for a number of reasons, users often go rogue, using products in ways they weren’t designed to be used.

Design for misuse is one way to counteract this and prevent unintended consequences. Design for misuse anticipates how an end-user might misuse a device. The principle uses design to make misuse impossible or to minimize the chance of a negative outcome.

Design for misuse is the notion of designing a product to deal with scenarios when users aren’t at their best.

Design for Misuse design principle

Humans Make Mistakes

The overarching idea is that humans are, well, human. Even if we’re capable individuals most of the time, we all mess up.

If a doctor is sleep-deprived, how is she likely to misuse a medical device? If a driver is texting while driving, what errors is he likely to make? How can designers and engineers make products that take this into account? And how can we design these products so their users are still able to accomplish necessary tasks?

Design for misuse is less about modifying users’ behavior and more about allowing a tool to continue to be functional, given the likelihood of certain behavior.

Four Ways to Design for Misuse

There are different approaches to design for misuse, and with a little foresight, you can intercept issues your users might encounter.

1. Predict Misuse With User Research

First and foremost, it’s necessary to do user research to understand when, where, and how people are likely to misuse a device. It’s often best to observe users in the field to see what real-world challenges might arise.

Remember that users are often on their best behavior when they’re testing a product under supervision. Consider how they will use the product when no one is watching.

2. Design For Ease Of Use

In its simplest form, design for misuse plays out as design for ease of use. The more difficult it is to use a product, the greater the chance of error.

To design for ease of use, we can turn to supporting principles like Hick’s Law and Mapping. Hick’s Law says that too many options negatively impact a user’s experience and make it harder to complete a task. To avoid this, follow the golden rule: keep it simple and straightforward.

Mapping, which is the relationship between controls and their movements or effects, can also help. Good mapping occurs when the effect corresponds to your users’ expectations. Intuitive controls reduce the chance of misuse.

Can you reduce the number of buttons on your device? Can you make it more obvious what each button controls?

3. Include Safeguards

In his book, The Design of Everyday Things, Don Norman writes about a Swiss Cheese Model of errors.

Don Norman's Swiss Cheese Model of errors from his book, "The Design of Everyday Things"

Ideally, you want your cheese (or product) without holes (errors), but if there are going to be holes, it’s a good idea to increase the layers of cheese (number of barriers) to minimize the holes (chances of failure).

The idea is that many factors contribute to errors, and by stacking safeguards, designers can reduce the chances that those errors will occur. The principle is used in industries ranging from healthcare to aviation and engineering, and it can be helpful in product design, too.

4. Communicate With Your Users

It is best to notify users when they’re about to go wrong or step off the expected path.

You experience this every time you go to delete something from your computer, and it asks, “Are you sure you want to permanently delete this file?”

Design Defined: Design for Misuse video

These conversations between machine and user prevents unintended actions. They are manifestations of the rule: Always include an undo. Many machines don’t. Many simply respond to an error by executing it.

What if, instead, the machine asked for clarification to determine the user’s real intended action?

Thanks to the Internet of Things, products are able to interact with users in new ways. Many connected devices can verify the things we’re asking them to do and can receive real-time feedback on system errors. The best products will take advantage of these IoT-powered capabilities.

Preventing Medical Device Misuse

When Alcon asked Bresslergroup to design a disposable scalpel with a retractable blade guard to protect doctors and nurses from accidental injuries during cataract surgeries, we started with user research. Our team conducted one-on-one interviews and observed surgeries, as well as pre-surgery prep.

We noticed that even with the blade guard, surgeons were at risk of injury because they kept their eyes focused on the view through a binocular microscope while using and transferring scalpels.

To mitigate that potential misuse, we designed the scalpel with a few additional safety features, like an ambidextrous orientation, an anti-roll rib, and a prominent activation button with clear tactile and audible feedback.

Avoiding Misuse in High-Stakes Environments

When D7 Systems sought Bresslergroup’s help designing the BDAS+ (Biological Decontaminant Accelerated Spray Plus), a portable application system to help military and first-responders neutralize biological threats, we knew that users would be wearing protective gear and working in highly stressful circumstances. Both of these factors are likely to increase the chance of error.

To reduce the likelihood of misuse, we designed the handle to be used by someone wearing heavy rubber gloves. We made the squeeze trigger ambidextrous with enough feedback to let the user know it’s being activated, and we made sure that BDAS+ can be sprayed from any angle, even when it’s upside down. A bright yellow safety tab and trigger communicate the correct operation, and the high-impact plastic is drop-resistant.

We considered what might go wrong and included preventative measures in the final design.

How Can You Design for Misuse?

Design for misuse is a reminder that good design is often not good enough. When you’re designing a product, don’t just address the technical challenges. Also keep in mind the problems your end-user might face in a social context.

What challenges might users encounter? When user actions go awry, how can your product prevent unintended consequences? Can your device verify users’ intentions? What physical and digital solutions can you offer to right the ship when a user goes rogue?

Learn about more product design principles when you download our free Design Defined ebooks, v1 and 2!